Allow user to mark a post as static page

- Increased post-settings width to properly display "Static Page"
- Changed templates to display "Static Page" if set
- Added unit test for body_class helper
- Added "page" class to both body_class and page_class

fixes #969

![selection_003](https://f.cloud.github.com/assets/176576/1351425/f7bc56c8-3724-11e3-9c7a-c1ce88d4bdb3.png)
![selection_004](https://f.cloud.github.com/assets/176576/1351426/f7e38bda-3724-11e3-941b-62fb2013516b.png)
![selection_005](https://f.cloud.github.com/assets/176576/1351427/f80a68f4-3724-11e3-97b3-eb9eaf866085.png)